THERE'S NO DOUBT that inpatient billing can be tremendously confusing, given the complexity of patients and the number of physicians called in to treat them. That makes untangling billable services a real challenge, with physicians and coders struggling to determine who provided which services and how those services should be billed.

Adding to the confusion are shift changes, critical care time, add-on codes and specialty designations. So how do you make sure that you're capturing all the revenue you're due?

In figuring out how to navigate your way through billing choices, keep in

Two physicians billing for the same patient on the same date may need different diagnoses to avoid a denial.

mind that the descriptors for both initial hospital visits (99221-99223) and subsequent visits (99231-99233) contain the phrase "per day" to designate services provided during an entire day.

"Per day" refers to one specific calendar date, not a 24-hour time period. You can bill only one visit per day, whether that's an admission or a subsequent visit, so your "one-a-day" claim needs to include all the services provided by all the physicians of the same specialty within your group. That means that you should combine all physician visits and services (for your group) during that calendar day, and select the code that reflects the sum of the work provided.

Sounds simple, right? But let's look at some common scenarios that may not be so straightforward.

Hospitalist A admits a patient while Hospitalist B, who's in the same group, rounds on that patient later that same calendar day.

In this scenario, both physicians are of the same specialty and in the same group, so the group should code and bill only an admission. Be sure to consider the level of services performed by both physicians, however, when determining which level of admission code to bill.

Hospitalist A admits a patient in the morning. That evening, the patient is seen by Specialist B, who is in the same group practice but has a different specialty.

Because the doctors have different specialties, Hospitalist A should bill for the admission. Specialist B, meanwhile, should bill for his or her hospital care, as long as documentation supports the medical necessity of both visits.

Hospitalist A admits a patient who later winds up in the ICU under the care of Intensivist B, who provides critical care.

Even if the hospitalist and the intensivist are in the same group, they have different specialties. Therefore, Hospitalist A would bill for the admission, while Intensivist B would bill for the time spent providing critical care.

Hospitalist A and Intensivist B both provide critical care in the ICU. Hospitalist A is managing the patient's blood pressure and blood gases, while Intensivist B is managing the vent and pressors.

As long as documentation supports the medical necessity of services from both doctors, each physician would bill for his or her services individually.

Those services may or may not be critical care¡ªbut if both physicians charge critical care time, they need to make sure that the two periods of time in which critical care was provided do not overlap.

Hospitalist A admits a patient in the morning who crashes that afternoon. Hospitalist A then moves the patient to ICU and provides two hours of critical care services. The total time spent with the patient that day is three hours.

Hospitalist A can bill both the admission and the critical care time¡ªas long as the critical care event occurred after the history and physical have been performed. You may have to submit documentation to support being paid for both services. A source that supports billing for both an admission and critical care on the same day is chapter 12, section 30.6.12, of the "Medicare Claims Processing Manual."

A critically ill patient presents to the hospital. Hospitalist A spends one hour stabilizing that patient, then rounds on that patient later the same day.

The patient required critical care at the time of admission prior to any E&M services being provided. Therefore, the hospitalist can bill only the critical care time, not an initial visit.

Hospitalist A provides one hour of critical care to an ICU patient in the morning, while Hospitalist B provides two hours of critical care services to that patient during the evening of the same calendar date. Both physicians are in the same group.

According to the "Medicare Claims Processing Manual," chapter 12, section 30.6.5, because both physicians are of the same specialty and in the same group practice, they need to combine their respective critical care times and bill for the total service under one doctor's provider transaction access number (PTAN).

That means that Hospitalist A would first bill 99291 (critical care for the first hour) plus a 99292 with 4 units (critical care for each additional 30 minutes). (To indicate those four units, you can write "X4" or put the total number of critical care minutes in, and the coder will figure out what number to put in the unit field.)

CPT code 99292 is an add-on code, so you need to bill that with Hospitalist A's critical service code 99291. Nothing, however, would be coded or billed for Hospitalist B.

Finally, let's take the same example as above, but make Hospitalist A and Hospitalist B different specialties, with Hospitalist B being a pulmonologist.

Each physician could bill for his or her critical care time with 99291, as long as the times billed do not overlap.

All of these scenarios come with the same caveat: Any time multiple physicians are caring for the same patient, they must establish and document the medical necessity of each of their services.

What this often means is that two physicians billing for the same patient on the same date of service will likely need different diagnoses to avoid a denial, regardless of whether or not those doctors belong to different specialties and/or groups.

Remember too that you'll have to rely on documentation to appeal a claim if it's denied. Make sure your documentation clearly reflects the diagnoses you addressed and the full picture of the patient's illness, as well as the medical need for your services.

Kristy Welker is an independent medical coding consultant based in San Diego. E-mail your documentation and coding questions to her at kristywelker@hotmail.com. We'll try to answer your questions in a future issue of Today's Hospitalist.